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pex tubing for compressed air lines?

Yeah, I know you are supposed to use black iron. I did that at my other shop. It worked well, but I never got all the leaks out. Plus- it is a PAIN to rearrange.

I am in a situation where I want to run some permanent air lines that I know will be changing at some point in the future. My barn/workshop will continue to be a work in progress for years to come, and machines and work areas will evolve.

I have some left over 1/2" pex and the (expensive) crimpers. I've had very good luck with this stuff with regard to no leaks. I once re-plumbed a house with it- no leaks at all- and this was the first time I ever used it.

The tubing itself is rated plenty high enough in terms of pressure. I know that PVC pipe is a bad idea (although plenty of folks do it). I can't see how pex would present any sort of danger, as it is not at all brittle.

It is very easy to run and snake around where you need it. I figure I'd still do the condensation drain drops like they suggest for iron piping. Or maybe I'd do a hybrid approach- iron for the main runs and pex for branches to specific areas.

Lynn,
I do have some experence with PEX and air. I ran 7/8 PEX in between all my floor joists of my shop for my radiant floor heating project a few years ago. I had a crimp in one of the lines and was trying to work it out. I added about 50lbs of air to the line and then applied some heat from a heat gun to the crimp. I figured I couldn't make it worse, and it might fix it. Well, I heated and squeezed on the crimp several times with not much luck. So I thought I need to get it hotter. Well I did, and BOOM! it blew up! Scared the pea wadden pudden out of me!!!! I had my face within about 12 inches fo the blowout, and all I got was a big puff of air in my face. After I finally realized I was ok, I checked out the tubing and found it had only a slit about 2-3 inches long.
Now I don't know if this story has any relevence to what you are asking, use it for what it's worth. What it tells me is that PEX probably won't cause lots of damage if it ruptures under air pressure like PVC would, but it is also may not best choice for an air line due, especially if it is exposed to heat or being punctured etc. I know I would't use it for air. I think copper would be the better choice. But, man!!! is it expensive these days.

Larry J Browning
There are 10 kinds of people in this world; Those who understand binary and those who don't.

There are pex-like plastic air-lines available with push-in fittings. It is very durable stuff and couldn't be easier to install. I believe we get ours through MSC or McMaster-Carr. It is designed for just the kind of things you want to do and is used extensively in industrial environments.

PEX is not rated for air and will break down with uv rays. I've checked with PEX and this is what they say. If you want plastic air lines look up Chemaire. It is truly rated for airlines. It's not cheap but it goes up easy and quick. L and K copper are ok for airlines. As most know PVC is not. Clearly stated in the OSHA rules.

There are pex-like plastic air-lines available with push-in fittings. It is very durable stuff and couldn't be easier to install. I believe we get ours through MSC or McMaster-Carr. It is designed for just the kind of things you want to do and is used extensively in industrial environments.

I have seen articles promoting the use of regular 1/2" rubber air hose for shop installations (vs. 3/8", for better volume). I would think that would satisfy your needs, other than tha fact that you have the PEX left over. Even so, the cost of the air hose is not that great, and easy and flexible to install.

On the other hand, not rated for air use does not necessarily mean not safe, if you can somehow saatisfy yourself that the PEX does not present a danger. I wouldn't worry about the UV concern if it is indoors. If there is any doubt, I would go with the air hose, unless you bite the bullet and use copper.

I sent an email to a company that supplies PEX (pexconnection.com) here is what he said when I asked about using PEX for compressed air in a hobby woodworking shop

" Air is routinely used for pressure testing PEX plumbing systems, and we use it here to distribute the air for our air compressor, so I would say that it should not be a problem for you to do that."

Then I asked about exposure to fluorescent lights in my shop. And his reply was:"For best results, you will most likely need to cover it. PEX should not be exposed to direct UV light for more than 30 days. I will say, however, that the PEX we are using (for water and air) is exposed to direct fluorescent light and indirect sunlight and is performing well. Still, the recommendation is that it not be exposed to UV light."

I used PEX for the first time to move a toilet supply in our basement. It is so much nicer to work with than copper.

Step into the 21st century and use the pex. 3/4" for main lines and 1/2" for for short runs if you must. I have a lot of experience with pex and I am amazed how well the stuff works. Keep it out of direct light and away from heat and it will last forever. (Or a very long time anyway). Also keep the pressure below 150. I just can't see how it could present any saftey hazard. Joe